Twin SU's

Post by **mike.perry** » Tue May 05, 2009 11:33 pm

Very nice installation. You've even used new nuts and bolts!
I see what you mean by the rear float chamber would be close to the exhaust pipe. Maybe with a 4 branch and some spacers you would have room for it, but then it might be too close to the bulkhead crossmember. I think it definately needs a heat shield.
I have a couple of old carbs and a twin carb inlet manifold I will have a play with them.
When I put the twin carb Midget engine in the Traveller I needed extra spacers to clear the 3 branch exhaust and then there was only just room for the K&N filter next to the wiper motor

Post by **RobThomas** » Wed May 06, 2009 10:58 am

I have the same carbs but with zero degree float chambers and longer, by about an inch or two, inlet tracts. Might be possible to get a heatshield in there more easily with the carbs further outboard plus you'd have a better chance of having a bunch-of-bananas exhaust manifold under there.

Doesn't detract from the fact that your kit looks like the Mutts Nuts!!!<br>

<br>

Post by **RobThomas** » Wed May 06, 2009 11:04 am

Having the middle 2 exhaust stubs come outboard more will allow all 4 pipes to be of equal length which aids exhaust pulse extraction (In theory?) There is enough of a gap at the rear for a float chamber to fit between the carb body and the crossmember without getting smacked but it won't work if the exhaust manifold is the standard item.

Keith. Do you have a photo of the Burgess/Derrington item that you were thinking of having copied?

Cheers

Post by **alanworland** » Wed May 06, 2009 2:07 pm

Mike, you kmow what happens when you start to have a play!
Rob, I am sure that there was space to fit float chambers outboard of the carb bodies (dont forget mine are inlined up) but it seemed neater to have them inboard - I shall see how the heat affects them once 'summer' arrives!
As the subject of exhaust has been raised, Keith, is there any news about the 4 branch copies yet?

Post by **mike.perry** » Wed May 06, 2009 6:11 pm

Alan,

Can you make it to the Series MM rally, it would be great to see your car and compare notes. There should be a selection of tuned MMs, Alex from Minor Mania is booked in with his Derrington, Graham should be there with his Alta and of course Keith will have his supercharged MM. I'll see what I can put together out of my box of bits.
The thing that is stopping me fitting twins is that I am very reluctent to start hacking my only manifold about and the fact that I can never get the carbs on the Midget engine properly balanced.

Post by **alanworland** » Wed May 06, 2009 10:33 pm

Mike, Possibly be able to come up on the Saturday, what times kick off?
I started to modify a Sprite inlet manifold but it was clear that it needed more work on than I initially thought! so thats how I started making my own.

Post by **mike.perry** » Thu May 07, 2009 9:10 am

I'll be there so turn up as early or late as you like.
If you can make it just click on events and fill in an entry form

Post by **tortron** » Sun Jun 28, 2009 3:58 am

tip for young players
there is a cavity that goes up between the two centre exhaust ports and next to the inlet. Possibly to preheat the fuel for emissions reasons?
i ended up cutting this off flat inline with the rest of the manifold, grinding it down and plugging it up with a mig welder.

Post by **tortron** » Sun Oct 25, 2009 4:11 am

well i have built my manifolds, linkages and adapted the airfilters
here is the finished result (almost, not shown are the manifolds i made up)

currently looking very nice bolted to the engine (shiniest parts in there)

Has there been any consensus as to what the "best" needles to use are? I currently have EK needles

Post by **mike.perry** » Sun Oct 25, 2009 5:43 pm

Ek are the strange profile standard needles but my preference is for M9s on the basis that they are richer at the top end but you don't need to use the top end unless you want to put your foot down.
If you go to http://www.mintylamb.co.uk/suneedle and enter the needle codes it will show you the comparative profiles.

Post by **alanworland** » Sun Oct 25, 2009 8:34 pm

Good link Mike, it really shows what a lot of words couldn't!
With my setup I started with the original EK's but have since fitted M9's and found them much better all round. I found to get a correct running mixture (as indicated by plug colour) the idle mixture was too rich - which is now much improved.
Your setup will probably totally different, but I have ended up with both jets wound down '6 flats' from the fully up position.

Post by **tortron** » Mon Oct 26, 2009 1:23 am

will have a look through the site and figure out what im after (ideally a big box of needles so i can chop and change as i please)

I have a colourtune kit here, so will see how that goes in tuning them

Post by **alanworland** » Mon Oct 26, 2009 11:55 pm

I have a colourtune kit and found it of limited value - best check is to go for a good fast run of several miles, then stop swiftly turning the engine off asap so the plugs retain their 'running colour' then make adjustments based on what you find - then repeat!

Post by **tortron** » Tue Oct 27, 2009 4:00 am

typically i use a vacuum gauge to tune the morrie (well its usually by ear now - lots of practice)
will be running them without a balance pipe and see how that goes

Post by **RobThomas** » Tue Oct 27, 2009 4:49 pm

I've used this wideband lambda kit for both the Mog and an aeroplane engine. Fantasticly accurate real-time data. I'm in Cardiff if you ever want to try it.

Post by **tortron** » Wed Oct 28, 2009 3:48 am

i think you would have to fly
i am NZ based

Post by **tortron** » Wed Oct 28, 2009 9:59 am

came across this ad in my searches

check out the downdraught su and exhaust on the right

Post by **alanworland** » Wed Oct 28, 2009 8:17 pm

Great old ad! I wonder how the carb dashpot gets on laying on its side?

Post by **tortron** » Wed Oct 28, 2009 8:19 pm

talking to a couple of guys who have mounted su's like that on bikes - its fine as long as you have the hole in the cap facing up. Wants to have good seals around the choke however

Post by **MikeNash** » Fri Oct 30, 2009 7:30 pm

Rob Thomas,
Can you tell us about your Lambda kit? Is it stand alone? did you make it? Love to have one, MikeN.